在 SQL 中加入来自同一个表的两个外键 [英] join on two foreign keys from same table in SQL

问题描述

不太清楚如何问这个问题，所以如果有人想编辑以更好地表达，请.但是我想加入一个用户表，但是该行有两个来自用户表的 FK

Not quite sure how to ask this question so if someone wants to edit to better articulate please. However I want to join on a user table however the row has two FKs from the user table

item_tbl
id | ownerId | lastModifiedById | itemName
------------------------------------------
1  |       1 |                2 | "Blog Post"

user_tbl
id | username
-------------
1  |     John
2  |    Sally

期望的输出(或类似的东西)

Desired output (or something like it)

Owner Username | last modified by |       item
----------------------------------------------
          John |            Sally | "Blog Post"

目前我正在执行两个查询来获取此信息.有没有更好(阅读:更有效)的方法?

currently i'm doing two queries to get this information. Is there a better (read: more efficient) way?

推荐答案

SELECT user_tbl.username Owner, a.username Modifier, item_tbl.itemName 
FROM item_tbl 
JOIN user_tbl 
ON item_tbl.ownerId = user_tbl.id 
JOIN user_tbl a 
ON item_tbl.lastModifiedById = a.id;

为那些好奇的人工作，正如 Drew 在评论中暗示的那样

worked for those curious as hinted at by Drew in comments

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